Honda Insight Forum banner

1 - 20 of 46 Posts

·
Premium Member
Joined
·
1,009 Posts
Discussion Starter #1 (Edited)
Insight Coolant Flow Diagram Gen 1



Begin edit Jan 2015
It has been brought to my attention that there exists a discrepancy between the Service Manual and the Parts pages from Honda on this subject.
Thanks Sean:D

On page 10-4 of the SM, the hoses going into and out of, the Idle Air Control Valve (IAC) or reversed from the parts diagrams.

I don't think this makes any difference in real time.
As a matter of fact, when I installed my satellite coolant pump, I used the parts diagram path. No problems or codes.
Randall
End edit Jan 2015


Original post starts here:
As we explore the coolant flow path, a few things may help us understand how the coolant gets from one point to another:

1. Fluid seeks it own level.

2. The pump in any system creates a pressure differential of some degree, from one side of the pump to the other.

3. Fluid will take the path of least resistance, whether it is flowing down a hill in the great outdoors, or circulating through a closed system, (for our purposes we will overlook the overflow jug, and consider the coolant system closed) with different diameters of pipe, hose, or tubing available for it to flow through. A bigger diameter will have a greater flow than a smaller one right next to it, in the same system.

4. In a closed system, once the fluid reaches the highest point, gravity helps out the flow, because as the gravity pulls the fluid to the lowest point in the loop, it pulls the fluid up the other side. This is known as siphoning. So from a dead start, the pump in a closed system has to overcome some initial amount of elevation change (known as maximum head), and then it is left to deal with the internal resistance of the plumbing, as once the siphoning starts helping out, the head falls back to, shall we say, an insignificant residual amount.



To start our exploration, we will turn the climate control temperature knob to its lowest setting (off), and also say that the engine thermostat is closed. There is no coolant allowed to flow through the primary radiator at the front of the vehicle, nor through the secondary radiator we know as the cabin heater core. With the engine running and thus turning the water pump, we have flow in the engine coolant path.

Let’s begin at the outlet port of the water pump where it mates with the engine block. The path is into the block, around all 3 cylinders, up into the head, and out of the right end of the head into the water outlet cover. All coolant leaving the pump, must take this part of the path.

The coolant temperature sending unit is mounted in the lower back side of the water cover outlet and is exposed to the hottest coolant just as the coolant exits the head and enters the water outlet cover. Now the coolant has some options for flow path. The upper yellow part of the water cover outlet is the housing for the TDC sensors, of which there are 2. Items in yellow are not part of the coolant path. Oh, and about the colors; I used red indicating hot coolant, until the flow path went thru something that would potentially lower the coolant temperature, and then I used blue from that device on toward the water pump. Yes, your right; everything is a heat exchanger, even the plumbing.

Most of the coolant will now flow out through port #11, following path #11 to the water pump. Ok, let’s get that oil warmer thing out of our hair. This item was discontinued begin with model year 2004. I have on hand a water pump from a 2004, and neither of the oil warmer connections are present on this later model pump. These would be the elbow fitting below the thermostat and the hard line T fitting that comes out of path #11 at the water pump. (For reference, my Insight is model year 2001, so I’ve got the oil warmer.) Not done with the oil warmer yet, but we need to bring another path of coolant flow into the picture before we can dismiss the oil warmer. We have most of the coolant flow through path #11, but there is also a smaller volume coming out of the small vertical port #5 on the water cover outlet, and flowing through the small hardline view #5(red) that is mated to the hardline air vent(yellow), which goes from the head cover to the air filter. Path #5 hardline turns into flexible hose and connects to the idle air control valve. Coming out of the idle air control valve it is dumped into path #8 at the green fitting. Let’s end path #5 at the green fitting. At this point there is no flow between port #8 on the water cover outlet and the green circle, because the climate control temperature is turned all the way down (off), and no coolant is flowing through the cabin radiator. So, at the green fitting the flow goes toward the water pump, where it flows over and around the thermostat. Path #11 and path #8 are mixed inside the thermostat housing, just before the flow goes around the thermostat (picture of thermostat housing in a following post will help us see how this mixing takes place). Both the in and out ports of the oil warmer are on the same side (intake) of the water pump impeller, and thus in the same pressure zone for the purposes of our study. However, since path/port #11 is larger than path/port #5; which at this point #5 is all the flow that is coming through #8 from the green circle to the water pump, even though path/port #8 is physically larger than #11, I’m going to say the flow goes through the oil warmer as I have depicted it. Path of least resistance. More flow coming in from #11 than from #5, although the lines running to and from the oil warmer are the same size as path #5. The oil warmer is just a loop, the ends of which are in very, very close proximity to each other. I would even entertain the idea of a venturi effect at the hardline T-fitting on the thermostat housing. If this were the case, the flow through the oil warmer could be in the other direction. We could pull some hoses with the engine running and see which way it’s going. Perhaps the flow becomes stagnant inside the oil warmer, and that is why Honda discontinued it.

OIL WARMER DISMISSED!!!!

Through its shortest path, the coolant is flowing from the pump, through the block and head, into the water cover outlet, out through port/view #11, which Honda calls a bypass pipe, and back to the pump, passing around the thermostat just before it encounters the impeller. Honorable mention is given for the flow through #5 to the IAC valve. Once the coolant gets up to temperature, the thermostat begins to open and allow lower temperature coolant from the primary radiator to join the flow. The outlet going to the radiator from the water cover outlet is connected internally with port #11, port #5, the bleed fitting, and the outlet going to the cabin heater. Any coolant coming through the thermostat from the radiator, is replaced by coolant exiting the water cover outlet. The hotter the thermostat is, the more it opens, and more coolant flows through the radiator.

Finally, we get to the cabin heat. Since our climate control is still set to the lowest temperature, there has been no flow thru the cabin heater core, and thus there has been no flow out of port #8. Port #8 is physically isolated from the hot coolant flow coming out of the head. Port #8 is connected only to the return from the cabin heater and the fill tube, which is the taller crooked fitting with the little black cap on it (picture in following post will help here also). With the cabin heat valve turned off there is no flow from the back side of the water cover outlet, through the cabin heater core, through the return line, back through the water cover outlet, out of port #8 and down to the green fitting. As the cabin heater control calls for heat, the valve opens and coolant makes the path through the heater core. This is the only way there can be any flow from port #8, to the green circle. The heater control valve regulates the flow through the cabin heater core in a manner similar to the thermostat regulating the flow through the primary radiator. Difference being, we don’t control the engine thermostat movement as we do the cabin heater valve.

Wow. We spent more time dismissing the oil warmer than we did looking at the rest of it. But, we needed to know what we learned while we were there.

Randall
 

·
Premium Member
Joined
·
1,009 Posts
Discussion Starter #2 (Edited)


This is the cylinder head mating surface of the water outlet cover. The nice machined round hole is where the end of the cam shaft sticks out, so the TDC sensors can do their thing. The lazy backwards LLLL shaped port is where the hot coolant exits the head and enters this water outlet cover.

Path/port #11 has the red ink pen stuck through it from the front.

Coming in from the left/back side is the coolant temp sending unit, not fully seated in its place. Just barely visible behind the temp sensor, is the passage #11 opening where the hot coolant would flow to the cabin heater.

The vent fitting is laying down on the paper in the lower part of the pic. Just a needle valve on steroids. Look way back in the deepest part of the casting and you can see a dark spot where the vent fitting would be mounted up on top.

Just forward in the cavity from that dark spot in the back where the bleed fitting goes, there is a pencil drawn arrow, on the internal casting, that points in both directions. This arrow is drawn to show how this part of the plumbing takes a dive under the hot coolant passage. This dive is part of the path #8 that is the return from the cabin heater to the hard-line plumbing port view #8 in the diagram. It is totally physically isolated from all other coolant passages in this outlet cover casting, with the exception of the little port #5 that goes to the IAC. There is also a pencil line drawn on the paper, to highlight the dip in the casting on the bottom side.

Randall
 

·
Premium Member
Joined
·
1,009 Posts
Discussion Starter #4 (Edited)


Here is the thermostat/water pump housing. We are looking directly into the opening where the thermostat would be mounted. You likely can’t get this view with the pump housing still mounted on the block. In this pic, the red pen is coming in from path #11. Were this an early model pump, there would be a T-fitting which would point down from the fitting where the pen is inserted. This path #11 fitting is behind the bigger one which is path #8 coming back from the cabin heater. Also on the early model pumps the hard-line elbow fitting would be pressed in where the little poly line is stuck into the casting recess in the pic.

Now we can see how the coolant from both path #11 and path #8 are mixed (spoken of in the first post) just before they pass over the thermostat and are subject to the pump impeller. Take a look at the thermostat itself in the upper right corner of the pic. See that little round flat metal washer on the very bottom? That goes down into the counter bore with the wall missing at about 3 o’clock. When the thermostat is closed, and no coolant is coming in from the radiator, flow #11 comes in from behind the little metal washer and around the washer through the omitted counter bore wall at 3 o’clock. Here it mixes with flow #8. As the thermostat opens, and more so the farther it opens; this counter bore will become increasingly sealed off by the little flat metal washer on the thermostat, closing down flow #11. This forces flow #11 coolant to join the path through the upper radiator hose coming from the water outlet cover and going to the primary radiator at the front of the Insight.


Randall
 

·
Registered
Joined
·
4,008 Posts
Wow.

--Sam
 

·
Registered
Joined
·
922 Posts
Randall, nice to see you on the site again. Thanks for posting, but I can only see the top half of Pictures #1 & 4. Please repair. Thanks.:)

Oops, it works in Firefox, not IE.

Oops2, computer fixed itself. Me bad
 

·
Moderator
Joined
·
7,181 Posts
Very interesting! Thanks for posting. :)
 

·
Premium Member
Joined
·
1,009 Posts
Discussion Starter #8
coolant flow diagram picture

Greetings guys,

I searched and searched but just could not find anything like that diagram anywhere here on IC, or in any of the manuals that I have.
If anyone needs a hard copy to take out to the vehicle or to the mechanic, drop me a PM, and I can forward the original. It fits on 11x17 and is very easy to read. Had to down size it to get it here. Or if you just want a copy.

Thanks to Jeff652 for a nice transaction on the salvage parts. Didn't want to take mine apart. Yet.

I'm assuming at this point that there are no problems with the modified Honda documents, being posted. If not mods notify me and we'll do something different. Gave credit and not selling anything, so figured it was alright.

Thanks,
Randall
 

·
Registered
Joined
·
2,312 Posts
Thanks Randall,

This is a great discription of how the entire coolant system operates. I had been wondering why there were so many extra tubes and pipes for such a small engine.

Great job!
 

·
Premium Member
Joined
·
2,885 Posts
Great write up / post ... many thanks.
 

·
Lean Burn = Happiness
Joined
·
2,155 Posts
Hahah Cool! Neat pics. Glad to be a part of this in a very small way! :D

Very informative! Those parts in the pics are off of a 2004 for documentations sake
 

·
Premium Member
Joined
·
1,009 Posts
Discussion Starter #12
dismissing the oil warmer

Thanks Jeff, I edited that year (2004) into the first post.

Have had some questions presented about the actual function of that oil/coolant interface, that Honda calls a warmer.

I see it acting as a temperature equalizer between the oil and coolant.
I labeled it warmer/cooler in the diagram, although Honda calls it only a warmer in their descriptions.

I question; once the entire mass of the ICE assembly, gets up to maximum operating temperature, this piece of hardware does nothing?
Randall
 

·
Lean Burn = Happiness
Joined
·
2,155 Posts
When I saw it, I immediately thought about how similar it looks to the oil cooler on some of the VTEC Integras. It's basically identical:


When I was racing, my oil temps would regularly get up over 280+ degrees. Running the oil through a water-to-water (oil to coolant) intercooler significantly reduces oil temperatures.

Edit: Just read your post that Honda has labeled this as a warmer on the Insight. Strange. Probably to warm the oil faster and keep it hot when the engine is doing start/stops around town
 

·
Premium Member
Joined
·
1,009 Posts
Discussion Starter #14
fixing coolant hardware problems

As the G1 Insight ages, we will begin to experience difficulty getting factory Honda parts. I read a post, found during searching for information on the coolant path, where the person had received notification from Honda that the part in question, was not in any of Honda’s US warehouses. This was one of the hardline coolant tubes that mounts to the water outlet cover, with an o-ring seal. I believe this hardline had corroded quite badly, and there was concern over re-installing it.

So, let’s look at options and scenarios that might present themselves, in regards to the cooling system parts and ways of dealing with those parts shortages, possible hardware damage, and some fixes to these problems.

Once again, we will encounter that oil warmer thing. Obviously, Honda decided this part could be eliminated, so we know we can do without it. Easy to work around when you don’t actually need it.

Simplest problem to fix would be if the outer housing of the warmer, became ruptured due to puncture from road hazard, or was eaten through by corrosion. The coolant flows inside the outer jacket in this item, and the oil flows in and out through the center portion, on its way to and from the oil filter. Provided there has been no breach between the oil and coolant passages of the oil warmer, we can just bypass it, even if caught away from home. Simply take either of the small hoses coming out the bottom of the water pump housing going to the warmer, and connect this hose, using a clamp, back to the other fitting on the water pump. Doesn’t matter if it has a kink in it, there will be no flow through this hose, nor is any needed. Check coolant level. Get back on road.

Once the warmer is no longer functioning as an integral part of the coolant system, we can physically remove it, if we wish. This will need to be done during an oil change, or the engine oil will need to be drained. We will also need the shorter oil filter mounting bolt from the 2004 and later model G1’s. Honda calls it “bolt, oil filter base”, PN 15560-PHM-000. After the oil filter is removed, take the longer original bolt out, remove the warmer and the thick aluminum spacer behind the warmer. Using the new shorter bolt, mount the aluminum spacer back to the block. The aluminum spacer has a key, on the bottom edge pointing toward the engine, that indexes against a boss on the engine block, which keeps the spacer from turning clockwise when the bolt is tightened. If notice is taken on disassembly, we can easily see how to put it back. Now we are back to something that feels familiar. Complete the oil change.

If we want our fix to look pretty, we can replace the possibly kinked hose running from one fitting on the pump housing to the other fitting, with a couple of those nifty little rubber caps, like up on the fill port. Same size plumbing. We would have needed to order 2 of them, known as; Cap, sealing PN 91657-SD5-000, when we ordered the short mounting bolt.

On my latest Honda parts order, I got the “not in any US warehouse” reply on the longer oil filter base mounting bolt for use with the oil warmer, on the 2000-2003 model years. Can’t say about the shorter bolt, haven’t tried ordering one of those yet. Wasn’t in need of the longer bolt, just wanted to take some measurements.

Randall
 

·
Administrator
Joined
·
11,586 Posts

·
Premium Member
Joined
·
1,009 Posts
Discussion Starter #16 (Edited)
possible replacement parts for cooling system

As the G1 Insight ages, we will begin to experience difficulty getting factory Honda parts. I read a post, found during searching for information on the coolant path, where the person had received notification from Honda that the part in question, was not in any of Honda’s US warehouses. This was one of the hardline coolant tubes that mounts to the water outlet cover, with an o-ring seal. I believe this hardline had corroded quite badly, and there was concern over re-installing it.

So, let’s look at options and scenarios that might present themselves, in regards to the cooling system parts and ways of dealing with those parts shortages, possible hardware damage, and some fixes to these problems.
I had gathering up some notes on the cooling system stuff, and need to get them posted before "wrote it down, but forgot where i put it", takes place.

About the connecting coolant hose from the hard line, view #8 on the coolant flow diagram; Honda PN #19503-PHM-000 HEATER PIPE, over to the water pump. Its the larger of the coolant hoses (not radiator hose) that is connected to the water pump.
The factory replacement for this hose is PN #19509-PHM-000. They were still available from Honda, last time I ordered, so I have one here in front of me to play with (plus a used one, thanks Jeff). The neck on the water pump measures (point 889/point 890) inches, which is 22.5mm. So this gives us the inside diameter of hose needed for a replacement. Didn't have much luck finding that size metric coolant hose.
However; I think we could push .875 inch, 7/8ID hose over those 2 pieces of hardware at either end of that hose. Still I find 7/8inch to be a rare animal.
Gates lists 3 PN's in their catalog for 7/8 molded coolant hose:
PN 19802 7/8 x 5.125
PN 21222 7/8 x 5.8125
PN 21746 7/8 x 6.3125

The factory hose 19509-PHM-000 measures 12cm along the bend, just short of 5 inches. Looks like any of the Gates hoses would work, even the shortest one needing to be trimmed slightly. The molded bend in some of them might be troublesome. Since I have the factory hose in hand, I will go to NAPA and see what the guys there can get for me of the Gates numbers. Can compare with the factory hose. I'll report back on this.

Now, about that hard line the member had trouble getting from Honda, the same we will talk about here PN 19503-PHM-000. I searched most all of the Honda models and years for something from the factory that might work. Other than the Insight that is, because the Insight parts are the ones disappearing off the radar. If we could find a late year model, perhaps we would have the needed replacement available for a longer time frame. The only thing I found close was Honda PN #19510-R40-A50 HEATER PIPE. Accord 2010 2dr EX; on the Water Hose L4 page. It is view #4 in the top corner. Looks like there has been an update, because view #13 is not listed (using Majestic parts page).
You will have to flop ends over to make it look like(fit) the one on the Insight diagram. It has the little fitting welded to it, that might be used for the smaller hose going down to the IAC. As long as we can cut it off past the little fitting, if it is too long. The reason I think this might work, is the o-ring size. The o-ring size on the Accord part is 19.3 x 3.8. The o-ring size on the Insight is 19.6 x 3.8. Point 3mm is not much. That's 12 thousandths (point 012) for we inch guys. Another reason this might work is the size of the smaller IAC hose fitting on both hard lines in question. On both the Accord part, and the Insight part, the hose clamp is the same PN #95002-41250-04 (D12.5). I couldn't find the actual size of the hose listed, but if the OD is the same, perhaps the ID is the same.

This hard line fix is not known for sure at this time. Just observation on my part. Next time I order factory parts, I will probably order the Accord part and see if it can be made to work. For 18 bucksUS inquiring minds want to know.:grin:

Another "get back on the road fix", might be to run bulk hose from the heater return on the firewall around to the water pump, bypassing the outlet cover/hard line all together. That would take the fill port out of the system, so that would need to be addressed, and the IAC would have to be taken out of the loop. But I haven't found any bulk 22.5mm hose.

More later.

Randall
 

·
Registered
Joined
·
93 Posts
I have an issue with the cabin heater in one of my Insights where it was working great and then it recently began blowing cold air. The problem was at first intermittent, but now it seems to always be cold air. The temperature gauge looks to be in the normal range as it always has been, but the OBDIIC&C is showing the ECT quickly rising to 240 degrees after about 10 minutes of driving. The OBDIIC&C is new, so I don't know what the ECT readings were for this car prior to the cabin heater issue. I don't question the OBDIIC&C gauge because it shows the ECT in my other Insight to be in a more normal 195-205 range.

The funny thing is that the car seems to be regulating the ECT at precisely 240 degrees. I already changed the 195 degree thermostat to a new 195 degree thermostat and that made no difference whatsoever. I tried another radiator cap. I followed the purge and fill tube/funnel routine several times. The serpentine belt was tight. I removed the water pump and it looks to be in great shape. The heater control valve is operating correctly as verified by removing the heater hose and observing operation of the solenoid operated ball valve. I have run water through the control valve/heater core and there doesn't seem to be any blockages. I have also run water through the radiator in both directions and there is no restrictions. I have also isolated and run water through most if not all of the hoses and no blockages have been identified.

I was wondering if anyone else has had a similar problem and what was the solution. Is it likely for the water outlet cover to become restricted? Possibly even a restriction to hot coolant but not to cold water while testing by use of a water hose? Is it also likely that the heater core is disallowing hot coolant to flow through, but allowing cold water from hose to flow right through?

I made an attempt at creating a simplified coolant flow diagram to visualize the various coolant flow paths throughout the system. Randall, please forgive me if I have misrepresented anything. I really appreciate you making your detailed drawing and explaination available on this thread!
 

·
Premium Member
2001 5S "Turbo"
Joined
·
10,579 Posts
8650
When you bled the system did you do it with the heater on and at the max. temp and the fan on high?

Willie
 

·
Registered
Joined
·
93 Posts
I'm pretty sure I had the temp control setting at the max, but let's hope I didn't because that would be the easy fix!

I'll re-install everything and then give the bleed and fill routine another try. At least on this car, the temp control knob controls the heater ball valve regardless of whether the heater is turned on and regardless of the fan setting, but I'll be sure to do those as well to be on the safe side.

If that solves the problem, then at least I had a great learning experience.
 
1 - 20 of 46 Posts
Top